Time to relapse after 6 and 12 months' treatment of generalized anxiety disorder with venlafaxine extended release.

CONTEXT: Generalized anxiety disorder (GAD) is a chronic disorder in need of reliable data to guide long-term treatment.

OBJECTIVES: To assess the benefits of 6 and 12 months' treatment of GAD with venlafaxine hydrochloride extended release (XR) in patients who improved after 6 months' open-label venlafaxine XR treatment.

DESIGN: After 6 months' open-label venlafaxine XR treatment, improved patients were randomized to venlafaxine XR or placebo for 6 months. All venlafaxine XR patients still in the study at 12 months were randomized to receive venlafaxine XR or placebo, and all placebo patients continued taking placebo for another 6 months.

SETTING: One urban site (5 locations).

PATIENTS: Of 268 patients with a diagnosis of GAD entering the open-label venlafaxine XR treatment phase, 158 (59.0%) completed 6 months, and 136 (50.7%) entered relapse phase 2 (6-12 months). Fifty-nine (43.4%) of 136 patients entered phase 3 (12-18 months).

INTERVENTION: Six months' open-label treatment with venlafaxine XR, followed by double-blind venlafaxine XR or placebo for 2 relapse phases, each lasting 6 months.

MAIN OUTCOME MEASURES: Time to relapse while receiving venlafaxine XR or placebo after 6 and after 12 months of treatment. Relapse was strictly defined to safeguard against assigning patients with venlafaxine XR discontinuation symptoms or temporary anxiety increase as relapse.

RESULTS: For objective 1, relapse rates in phase 2 (months 6-12) were 9.8% on venlafaxine XR and 53.7% on placebo (P < .001). For objective 2, relapse rates after 12 months on placebo (32.4%) were lower than after 6 months on venlafaxine XR (53.7%) (P < .03).

CONCLUSIONS: Treatment of GAD with an antidepressant should be continued for at least 12 months. Preliminary data demonstrate that improved patients who relapse while off their antianxiety medication after at least 6 months of treatment will again most likely respond to a second course of treatment with the same medication. Trial Registration clinicaltrials.gov Identifier: NCT00183274.